Rockwell Automation Allen-Bradley SynchLink 1756-DM Series Design Manual page 35

The bypass switch block has no capabilities to detect or correct
communication error conditions that may exist during the course of
pass-through or bypass operation. The bypass switch block has no
ability to report any abnormal conditions to the local station.
IMPORTANT
SynchLink Bypass Wiring Diagram
Figure 3.4 shows how to wire a SynchLink hub.
Figure 3.4
24V dc
power
supply
24V dc
common
+24V dc
To +24V dc terminal on local
node digital output
The Bypass Switch should be applied as a SynchLink
patch when a local node needs to be powered down
as a result of equipment reconfiguration (e.g. in
order to manufacture a variety of products on the
same process line) or a failure. It should not be
applied for dynamic switching between Pass
Through and Bypass modes; this may result in the
loss of time synchronization between nodes and the
loss of data transferred between them.
While the main point to remember is that bypass
switch should not be applied dynamically (i.e. while
power is applied), there are other uses for the
bypass switch (to be used in a powered down
environment), including:
· change topology configuration
· change masters in a topology
From local node To local node
1751-SLBP
To 24V dc common terminal
on local node digital output
To downstream node
From upstream node
43270
Publication 1756-TD008A-EN-P - August 2002
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